The present invention relates generally to assemblies used in the manufacture of metal containers. Particularly, the invention relates to a bottom forming assembly used in the drawing and forming of the bottom portions of two piece steel and aluminum cans.
The can bottom forming assembly of the present invention is an improvement of the bottom formers disclosed in U.S. Pat. No. 4,930,330 ('330 patent) to Weishalla, entitled Double Action Bottom Former, and U.S. Pat. No. 6,490,904 B1 ('904 patent) to Zauhar, entitled Double Action Bottom Former for High Cyclic Operation, both owned by the Assignee of the present invention. The bottom formers of the '330 and '904 patents, incorporated by reference herein, are constructed and arranged for cooperating use with a can bodymaker and specifically, the bodymaker punch carrying the can bodies. The '330 patent and the '904 patent disclose dome plug positioning structures for bottom forming assemblies. The present invention provides further improvements for can bottom forming assemblies.
The '330 and '904 patents disclose can bottom forming processes including the action of the punch or ram of a can bodymaker assembly with respect to a bottom forming assembly. Bottom forming assemblies are typically constructed and arranged to cooperate with bodymaker assemblies. The bottom former receives can bodies on the rapid cycling bodymaker punch and forms two piece can body bottoms through a drawing and final forming process utilizing a clamp ring and dome plug. The term clamp ring is also known in the industry as a pressure ring, guide ring or outer die. The term dome plug is also known in the industry as an inner die or dome post. The specific manufacture of cans, beverage or food, may determine the use of the particular term. Spatial control of the clamp or guide ring along and normal to the axis of ram movement is imperative for manufacturing quality, production and efficiency. The thicknesses of can body bottoms are becoming increasingly thinner requiring specified can bottom profiles to provide strength and which make manufacturing control imperative. Thus, increased clamp ring pressure and a more compact can bottom forming assembly aids in maintaining can bottom profile and thickness tolerances.
The bottom forming assemblies of the present invention provide a compact, lightweight, easy to maintain and service bottom forming assembly having a novel arrangement of components to provide the requisite clamp ring pressure and improving the centering and biasing control of the clamp ring.